Hand carts and "dollies" have been used for centuries in lifting and movably supporting heavy loads. The typical hand cart includes a rigid upright frame, having a handle at a top end and a pair of ground engaging wheels at a bottom end. A forwardly projecting ledge is usually provided at the bottom end of the frame for supporting the weight of the load adjacent the wheels. The load is supported on this ledge and the engaged portions of the cart frame. The wheel axis acts as a fulcrum point about which the load is tipped as the cart frame is inclined to lift the load. The wheels can then be used for transporting the load once the frame has been tipped far enough to lever the load upwardly from the ground surface.
The above standard cart form functions entirely serviceably where there is relatively free access to the underside of the load. Such access is required for proper placement of the forwardly projecting ledge under the load for lifting and transport. There are many objects that do not easily lend themselves to transport by such hand carts since there is no easy access underneath the load for the forwardly projecting cart edge.
Another common problem with typical hand carts is securing the load once it is in place upon the cart framework. A solution to this problem is disclosed in U.S. Pat. No. 2,510,676 to Biek. This patent discloses a hand cart of the typical form but including load engaging and gripping arms that extend from the cart frame. The arms are selectively pivoted by the cart frame handles. The operator must rotate both handles selectively to pivot the load engaging arms into and away from contact with the load. The operator can selectively maintain a gripping, stabilizing force on the load, or can selectively release the arms by rotating the handles appropriately. Two hands are required to perform this function and both must remain occupied on the handles so long as the gripping forces are required. Additionally, the arms are used only to stabilize the load as opposed to providing support. Support is provided by a forwardly projecting ledge at the bottom end of the cart frame, a feature typical of such hand carts as generally described above.
Certain forms of loads require special considerations, such as those indicated above where access beneath the load is limited. Other needs also come into consideration. For example, hay bales are unwiedly due to their fairly large size and weight. Most bales are typically tied with wire or string and are shaped in the form of a rectangular solid. The string or wire is wound in two individual loops about the long dimension of the bale. Handling techniques for such bales usually involve simple manual manipulation by hand wherein the strings are grasped and the bale is lifted by the strings, or by "hay hooks". While tractor mounted mechanical lifts have been developed for large, cylindrical bales (U.S. Pat. No. 4,073,532 to Blair), other methods for easing manual handling of the more common smaller rectangular bales has been limited.
One attempt at manual mechanization of bale handling is demonstrated in U.S. Pat. No. 4,174,849 to Wetzel. The apparatus described in this patent includes a wheelbarrow frame configuration with carrying members situated between a bottom single wheel and handles at an opposite end of an elongated frame. Bale engaging hooks are positioned on the frame with one stationary set position adjacent the wheel and one pivoted set situated adjacent the handle ends of the frame. The frame, hooks and wheel are constructed so the cart must be placed over a bale, with the operator situated on one side of the bale and the frame and wheel extending to an opposite side of the bale. The cart can then be pulled rearwardly to pull the stationary set of hooks into the adjacent bale end. The pivoted tines can then be swung downwardly into the opposite end of the bale to secure it in position in relation to the frame. The bale can then be lifted and transported while suspended from the hooks under the frame. The forward hooks are pivoted about an axis that is transverse to the longitudinal dimension of the frame and are swung manually into position. No provision is made for locking the hooks in a closed, operative position. Additionally, the hooks are positioned along the frame so that the bale must be engaged at opposite end surfaces. This arrangement therefore allows only a single bale to be engaged at a given time and allows for only a single length bale to be carried. This presents a problem since bales may vary in length dimensions.
The Blair patent briefly mentioned above deals with a handling device mounted to a tractor for lifting and handling large round bales. The device makes use of a hydraulically operated set of bale engaging tines mounted for partial rotation responsive to action of a hydraulic cylinder on a rigid frame. This frame is carried at the outward end of hydraulically pivoted arms mounted to the tractor. The tines spread to receive a portion of the round bale circumference. A considerable number of tines are provided to engage the bale circumference in order that the bale can be supported by the tines when the arm is lifted.
U.S. Pat. No. 1,255,070 to Waller and U.S. Pat. No. 2,278,950 to Smart both disclose hand carts or trucks with spring biased, normally closed gripping arms for engaging and releasably securing a load. The gripping arrangements are provided at a position angularly disposed from the cart frames. The angular relation between the frames and arms is such that an operator is required to push the frame handles downwardly to produce a lifting force at the load. While serviceable, these carts are large and substantially awkward to handle. They are also quite complex in construction.
U.S. Pat. No. 270,068 to Holman discloses another form of hand truck somewhat similar to the Waller and Smart trucks discussed above. The Holman truck includes forwardly projecting arched jaws that are normally sprung open to receive a load. The jaws are pivoted on pins with rearwardly extending lever arms leading to a cam operator. The cam operator is situated at the end of a long lever handle. The handle is pivoted to the frame for movement responsive to manual shifting of the lever from one side of the frame to another. Movement of the cam causes the lever arms to move the load gripping surfaces together or apart. A catch arrangement is provided adjacent an outward end of the handle for selectively securing the handle in a selected position. The catch prevents the gripping members from pivoting toward on open position but does not prevent them from swinging further closed. No positive locking capability is provided. Deformation of the load could therefore result in release of the gripping members and consequent disengagement of the cart and load. This is a very real possibility with loads, such as hay bales, that are capable of deformation. This also presents a problem where the gripping members penetrate the load. The handle can not be used to open the tines and release the load. There is no provision beyond the springs for accomplishing this function.
A problem has therefore remained in providing releasable, yet secure, load gripping members in a hand cart, along with features that eliminate the need for a forwardly projecting foot at the bottom end of the cart as has been needed to receive and support an engaged load. The present invention, as will be understood below, provides a new and unobvious solution to this problem.